This invention relates to piston and cylinder assemblies, and in particular, a control apparatus for use therewith.
Present commercial hydraulic or pneumatic piston and cylinder assemblies include a feature which permits the entrapment of a cushion of fluid at the end of the cylinder when the piston reaches the end of its stroke for reducing the speed at which the piston approaches the cylinder end and for preventing damage to the cylinder or piston by preventing the piston from striking or bottoming out against the cylinder end cap.
In commercial assemblies, this cushioning is obtained by providing the piston with a projection which extends from one end thereof and is adapted to fit into a bore in the cylinder end cap through which the fluid leaves the cylinder. In operation, near the end of the stroke the projection plugs the bore and traps a cushion of fluid between the cylinder cap and piston. This arrangement has the disadvantages that is requires expensive precision boring and formation of the two mating parts and is not readily adaptable for field installation to many types of cylinder assemblies.
Therefore, it is an object of this invention to provide a relatively inexpensive control apparatus for cushioning of pistons in cylinder assemblies and which can be adapted for field installation to many types of cylinder assemblies.
Another problem with existing cushioning arrangements is that the formation of the cushion or cushion size and the speed of the reduction or release of the cushion is not controllable.
It is, therefore, another object of this invention to provide a control apparatus which provides for controlling the cushion size and the speed of the cushion release.
These and other objects of this invention will become apparent from the following description and appended claims.